Cutting oil



Patented Dec. 1, 1942 I I u UNITED STATES PATENT 2,303,853 FFlCE CUTTING OIL William A. Lutz, Oakmont, and Edward R. Butcher, Harwick, Pa., assignorsto Gulf Re search & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application December 20,- 1940,

' Serial No. 371,03

- 7 Claims.

This invention relates to cutting oils; and it comprises a process of producing a high sulfur petroleum oil base for cutting oils, wherein the oil obtained on warming a cold sulfuric acid extract from a high sulfur cracked distillate, is

reacted with sulfur at a temperature of 300 to 375 F.- for a time suflicient to form a stable liquid reaction product and insuflicient to form a tarry mass; and it further comprises a cutting oil base which is a stable liquid reaction product of sulfur with the oil obtained on warming a cold sulfuric acid extract from a high sulfur cracked distillate; all as more fully hereinafter set forthand as claimed.

The cutting oils with which this invention is concerned are used to cool and lubricate the composition which is highly eflicient as a cutt g oil.

tools and work pieces in various metal forming operations, such as cutting, drilling, turning and the like. Satisfactory cutting oils are characterized by high heat absorbing power, stability under the high temperatures incident to their use, good wetting power, a viscosity which permits them to flow readily from the point of application and by being substantially non-corrosive to the metal surfaces being worked. Various types of oils have been used for this purpose including both animal and mineral oils.

saturated hydrocarbons, such as naphtha, motor fuels and the like, which have been produced from high sulfur crudes, it is often desirable to effect a separation and polymerization of sulfur compounds without removal of excessive amounts of the unsaturated hydrocarbons. For this purpose cracked petroleum distillates of high sulfur content are commonly subjected to treatment-- with cold concentrated sulfuric acid at temperatures on the order of to F. in the amount of 2 to 8 pounds per barrel of distillate.- By this treatment it has beenfound that desulfurization can be effected without substantial polymerization'or solution of the non-sulfur bearing hydrocarbons.

Upon warming the sulfuric acid extract re- I covered in this process, to room temperature or Lard oil, an animal oil, has been used extensively as a cutting-lubricant. However it is not stable and tends to develop gum forming properties with repeated use. Mineral oils particularly mineral oils to which certain sulfurized mineral oil products ,have been added have largely replaced animal oils as cutting lubricants and have proved more or less satisfactory. These sulfufized mineral oil bases for cutting oils are in many cases solutions or emulsions of sulfur in oil and they tend to break down and deposit sulfur on repeated use. Also the limited amount of -sulfur which it has been possible to combine with the oil has necessarily limited their use. -Sulfur has also been compounded with highly unsaturated mineral oil fractions, for example,

somewhat higher, an oil separates by gravity from the acid in substantial quantities. This cold sulfuric. acid extract oil is known as cycle oil and will be so referred to hereinafter and in the appended claims. The exact composition and properties of a cycle oil will vary somewhat with the composition of the oil originally treated, and

the extent of the sulfuric acid treatment. A typi- I cal cycle oil from a high-sulfur cracked gasoline,

" which had been washed with caustic soda solucracked distillate, to form relatively stable bases for cutting oils which are comparatively satisfactory.

The present invention provides'an improved sulfuri'zed mineral oil base for cutting oils which is stable and which has an exceptionally high combined sulfur content. This base when combined with a light mineral oil in suitable pro- 'tion to. remove traces of sulfuric acid, showed the following characteristics:

I TABLE I Properties of cycle foil :Gravity, A. P. I 18. 1

portions provides cutting oils which are quite stable and non-corrosive and which have very good cooling and lubricating properties.

We have discovered that the oil which separates by gravity from a cold sulfuric acid extract of a high sulfur light petroleum fraction upon raising the temperature of the acid to about room temperature is capable of reacting with sulfur under suitable conditions of time and temperature to form a stable fluid product which when dissolved in light petroleum oil gives a According to the present invention cycle oil obtained as above described is sulfurized to provide an improved cutting oil base having a high combined sulfur content.

In carrying out the preparation of a cutting oil base according to our invention, the cycle oil is heated to a temperature of 300 a relatively largeiamount of sulfur, usually about 20.0 to 30.0

' In the refining of cracked petroleum distil-j lates containing relatively large amounts of un- F. to 375 F.,'

per cent by weight, is added to the oil slowly and with continuous agitation and the temperature is maintained between about 300 and 375 for a time sufiicient to effect the formation of a stable reaction product between the sulfur and the oil. The time required to form a stable reaction product varies inversely with the temperature at which sulfurization is effected. The most satisfactory conditions for the reaction have been found to be treatment for about one hour at 340 to 350 F. 'At temperatures below 340 F. the reaction is relatively slow and longer periods of heating are required. If an' insufficient heating period is used, sulfur will separate out when the reaction product is subsequently diluted with oil to form the cutttin oil. At temperatures above 350 F. the reaction proceeds quite rapidly and shorter heating periods are required. If the mixture is heated too long it will turn into a viscoustarry mass unsuitable as a cutting on base.

The cutting on base prepared according to our invention is a black liquid miscible with mineral oils at temperatures of 125 to 150 F. It has an effective blending viscosity of about 750 tov 1000 S. U. V. at 100 F. and will ordinarily contain a little over 20.0 per cent by weight of sulfur. It may be blended with substantially any low viscosity mineral oil to obtain a cutting oil stable under ordinary conditions.

The amount of base to be blended with the light oil in forming a cutting oil may be varied over a relatively wide range depending upon the properties desired in the finished cutting oil and the properties of the mineral oil used. Usually an amount of the base corresponding to about 7.0 to 20.0 per cent by weight of the mineral oil is used. In most cases a finished cuttingoil containing about 3.0 per cent by weight of sulfur has been found satisfactory.

The flnishedcutting oils prepared according to our invention are more stable than the cutting oils heretofore available and possess exceptionally good lubricating qualities. Any slight odor they may have after mixing can be removed by steaming and no further odor is developed even on long standing. Furthermore after standing for relatively long periods they show no precipitation of sulfur, in contrast to the cutting oils now commercially available. When used in lathe work the chips produced show less galling and tearing than when conventional lard oil lubricants are used, indicating improved lubricating properties.

In the .following specific example there are illustrated the production of the cutting oil base of our invention and a cutting oil produced from said base.

A sample of cycle oil was heated rapidly with constant agitation to a temperature of 340 F. Flowers of sulfur in amount corresponding to about 20.0 per cent by ,Weight of the cycle on were slowly introduced with stirring while the temperature was raised to 350 F. The sulfur had dissolved by' the time the temperature had reached 350 F. The resulting mixture was held at 350 F. for one hour to complete the reaction. When cooled, the resulting product was a dark viscous mass readily soluble in mineral oil. 0n analysis this cutting oil base showed it to contain between 19.5 and 2L0 per cent sulfur.

The cutting oil base thus prepared was blended in amount corresponding to about 15.0 per blending precautions were necessary as the base blended readily withthe oil, but the temperature was raised to 125-150 F. to increase the rapidity of solution. There was produced a cutting voil having a viscosity at 100 F. of 107 S. U. 3., pour point of +25.0 F., flash point of 335 F., fire point of 385 F. and a sulfur content of 3.51 per cent.

The sulfurized cycle oils prepared according to our invention have also proved useful as addition agents for lubricating oils where the corrosion inhibiting value of sulfur compounds is required. While our invention has been described herein with reference to certain specific embodiments thereof, it is to be understood that the invention is not limited to the details of such embodimerits except as hereinafter defined-in the appended claims.

What we claim is: 1. A process of producing a high sulfur petroleum oil base for cutting oils comprising reacting an oil which is obtained on warming'the cold sulfuric acid extract from a high sulfur cracked distillate, with sulfur at a temperature of 300 to 375 F. for a time sufllcient to form a liquid reaction product which does not precipitate sulfur on dilution with a mineral oil, and insufllcicnt k to form a tar-like mass.

2. The process of producing a high sulfur petroleum oil base comprising reacting an oil which is obtained on warming the cold sulfuric acid extract from a high sulfur cracked distillate, with sulfur at a temperature of 340 to 350 F. for a time sufficient to form a liquid reaction product which does not precipitate sulfur on of the stable liquid reaction product produced by heating sulfur at a temperature of 300 to 375 F. with the oil obtainedon warming the cold sulfuric acid extract of a high sulfur petroleum oil, for a time sufficient to form a liquid reaction product which does not precipitate sulfur on dilution with a mineral oil and insumcient to form a tar-like mass.

cent by weight with about 51.0 per cent of 70/ 1.5 I

'5. A base for cutting oils consisting essentially of the stable liquid reaction product obtained by heating sulfur for about one .hour at a temperature of 340 to 350 F. with the oil obtained on warming the cold sulfuric acid extract of a high sulfur petroleum oil. 1 I

6. A sulfurized cycle oil'obtained by reacting sulfur for about one hour at a temperature of 340 to 350 F. with the oil obtained. on warming the cold sulfuric acid extract of a high sulfur petroleum oil.

7. A cutting oil comprising a light mineral oil and about 7.0 to 20.0 per cent of the stable liquid reaction product produced by heating sul- 

